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TOPIC: Audio out of sync

Re: Audio out of sync 3 years, 3 months ago #144175

  • hugly
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convert my videos to a fixed frame rate?

Yes, unfortunately.

To fix the problem with existing files you have to transcode them using third party software, Eyeframe converter, Handbrake, or FFmpeg (for example). Those programs support batch processing to let them run overnight.

My personal favorite is Eyeframe converter. It’s very easy to handle and produces perfectly editable files.

To prevent the problem in the future you have to use game capture software which supports constant frame rate settings, OBS for example. Additionally I would check whether 60 fps as recording frame rate can be handled by your hardware without generating lots of duplicate frames. 30 fps might be a better choice perhaps. I’ve read that there’s a physiological limit of appr. 48 frames per second for gameplay recordings, above that limit nobody is able to see any difference, even on 400 Hz or 800 Hz displays.
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Last Edit: 3 years, 3 months ago by hugly.

Re: Audio out of sync 3 years, 3 months ago #144179

  • khelrauko
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Okay. Firstly thanks for bearing with me on this.

I have two questions:

1) Why haven't I noticed this problem before? I've been using Lightworks and exactly this set up for months. Discounting, I've been lax until now, why only now?

2) I am correct in thinking that if I am to transfer these to dvd, anything above 30fps is worthless? I had the notion of keeping 60fps because I wanted the files at the highest frame rate for any future possible conversion. I may discount that if it saves all this heartache.

Re: Audio out of sync 3 years, 3 months ago #144182

  • khelrauko
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I've a third question: If I spot sync issues with sequences I have already edited, is there any way of rescuing them, or do I have to discard them and start again with a converted, fixed framerate file?

Re: Audio out of sync 3 years, 3 months ago #144187

  • hugly
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1) I really dont know. I'm not aware of any difference handling variable frame rates between V12.6 and V14. Both versions don't support it (nor any other NLE I know about) without sync issues.

2) I'm not aware of any DVD standard supporting a frame rate higher than NTSC 29.97 fps progressive and regular DVD's don't support HD (execpt using a DVD as simple file based data storage for any format). Even Blue Ray standard doesn't support 60 fps progressive, as far as I know. Most BD's produced today are 23.976 or 24 native. For recent blue ray standard 24 or 48 fps recording would be better to avoid artifacts caused by frame rate conversion from 60 fps to 24 fps.

3) Difficult, converting to a constant frame rate will add and remove frames, the cut points will move. The variability of the frame rate depends on recording conditions and is unpredictable. There might be some self compensating effects here or there. You can replace the originals with the transcoded files at exactly the same location (and name including extension) and then start Lightworks and see what happens.
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Re: Audio out of sync 3 years, 3 months ago #144192

  • khelrauko
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Thanks for your assistance and candour.

Well, that blows my weekend...

Re: Audio out of sync 3 years, 3 months ago #144204

  • briandrys
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Hard to tell the frame rate variations that may exist in this file compare to your other files, since only one file has had an analysis. How noticeable sync drifts are can depend on the nature of the audio and if there are any spot effects that register as sync points

Lightworks, like other professional NLEs doesn't like variable frame rates.

Re: Audio out of sync 3 years, 3 months ago #144314

  • khelrauko
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I take the point. The only concern for me is in over 10 hours of workflow, the only variable has been the change from 12.6 to 14.0 of Lightworks.

Re: Audio out of sync 3 years, 3 months ago #145632

  • bren7473
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I wanna jump on this too. Just updated to lightworks 14 and after making some FX changes to a project ive been editing for over 8 months realized that the audio is out of sync everywhere. If this is because of variable frame rates and this issue also existed in 12.6 then why didn't I ever once encounter it?

Re: Audio out of sync 3 years, 3 months ago #145633

  • bren7473
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As in I didn't move video or audio but all of a sudden everything is f'd up and it takes hours to fix. This needs to be fixed asap.

Re: Audio out of sync 3 years, 3 months ago #145640

  • briandrys
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Welcome to the forum.

Since we don't know anything about your media, other users can't pass comment on if it has a variable frame rate o not and possible solutions. Please follow the directions in this sticky, so that users can see the technical details of your video.

www.lwks.com/index.php?option=com_kunena&func=view&catid=23&id=66072&Itemid=81

Re: Audio out of sync 3 years, 3 months ago #145999

  • khelrauko
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To reiterate the point once again: I have over ten hours of footage edited in Lightworks 12.6 with no sync issues that I can identify. Yes, the footage is screen capture of variable frame rate video. It is now on 14.0 and was then on 12.6.

Why have I only encountered the variable frame rate issue post 14.0? It ducks the question, to demand media info, point at the variable frame rate and consider it job done.

The simple outcome of changing from Lightworks 12.6 to 14.0 (for me) is my files need to be 5 times the size and I have to pass them through third-party software before they will work.

So I ask, vainly, again: is there any way in which I can run Lightworks 12.6 without encountering the validation issue?

Re: Audio out of sync 3 years, 3 months ago #146004

  • hugly
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With a pro license you should be able to install Lightworks V12.6 and V14 on the same machine and run them with the same license, simply by using a different folder during installation (e.g. "Lightworks12", "Lightworks14").

If file size matters, you could use FFmpeg (or another program of your choice) to transcode to AVC with constant frame rate, one example:

ffmpeg -i "<INPUT>" -vsync cfr -c:v libx264 -pix_fmt yuv420p -profile:v high -preset veryfast -tune fastdecode -crf 20 -x264opts keyint=60 -c:a aac -b:a 256k  -y   "<OUTPUT>.MP4"
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Last Edit: 3 years, 3 months ago by hugly.

Re: Audio out of sync 3 years, 3 months ago #146019

  • bren7473
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Yep, I rolled back to 12.6 and everything works perfectly. Would be interested to know if this is a problem with porting projects or if it happens to new ones as well.

Re: Audio out of sync 3 years, 3 months ago #146029

  • donkpow
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I understand the frustration on this topic but it benefits one to understand that it is important to have properly formatted media for complex workflows. Simple editing tasks may be possible in AVC material as long as it is minimally compressed. For more complex workflows, edit friendly formats are essential.
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Re: Audio out of sync 3 years, 3 months ago #146048

  • hugly
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bren7473 wrote:
Yep, I rolled back to 12.6 and everything works perfectly. Would be interested to know if this is a problem with porting projects or if it happens to new ones as well.

You can test that easily by importing the same footage into a newly created project with V14 and compare yourself. You should use the same project settings creating the new project, and the same import method.

It's very unlikely that there is a difference between the versions dealing with variable frame rates, but if there should be, further information about your footage and your project settings and import method would be much appreciated.
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Last Edit: 3 years, 3 months ago by hugly.
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